In the field of imaging technology of an electrophotography system employing copiers or printers, there has recently been demanded a technology at a level of precise reproduction of minute dot images at a level of 1200 dpi (dpi: the number of dots per inch or 2.54 cm) along with advancement of digital technologies. In order to precisely reproduce fine dot images, miniaturization of the toner particle diameter has been studied, and much attention has been paid on a chemical toner such as a polymerization toner capable of controlling various matter properties produced in a manufacturing process (refer to Patent Document 1, for example).
The chemical toner is adapted to a recent environmental consideration trend, and be capable of an environmental conscious production of toner, since carbon dioxide emissions can be reduced during manufacturing. The polymerizable toner containing a low melting point wax is also capable of forming images fixed at lower temperature than before, whereby electric power consumed by apparatuses is to be reduced (refer to Patent Document 2, for example).
On the other hand, in order to conduct the stable image formation, it is desired that the toner is designed in such a way that no component of colorant or wax is exposed on the toner surface. Consequently, the toner having a so-called core/shell structure, in which a resin is coated around a layer containing a component of colorant or wax, is provided.
Disclosed as a technique of preparing the toner having a core/shell structure is a technique in which a core/shell structure is formed by fusing resin particles on the core surface prepared via association-fusing of resin particles and colorants (refer to Patent Document 3, for example). It is also desired that components contained in the toner seep into the toner surface efficiently in order to realize good image formation with the toner having a core/shell structure. Various studies concerning the shell thickness so as to make the toner components seep into the toner surface efficiently have been made, and disclosed, for example, is a technique relating to a manufacturing process of the toner having a shell thickness of approximately a few 100 nm (refer to Patent Documents 4 and 5, for example).
(Patent Document 1) Japanese Patent O.P.I. Publication No. 2000-214629
(Patent Document 2) Japanese Patent O.P.I. Publication No. 2001-42564
(Patent Document 3) Japanese Patent O.P.I. Publication No. 2002-116574
(Patent Document 4) Japanese Patent O.P.I. Publication No. 2002-359213
(Patent Document 5) Japanese Patent O.P.I. Publication No. 2004-109939